#include <stdio.h>

//https://www.nowcoder.com/practice/fc72951f52984f3abd286d82eeffacba?tpId=290&tags=&title=&difficulty=0&judgeStatus=0&rp=0&sourceUrl=%2Fexam%2Foj%2Fta%3FtpId%3D290

int main() {
    double num = 0;
    double sum = 0;
    scanf("%lf", &num);
    do {
        sum += 1 / num;
    } while (--num);
    printf("%f", sum);
    return 0;
}


